If you want to allow your editors upload of files only with the TYPO3 element browser you can do so with a simple TypoScript in the TSconfig of the root page.
The code have to look like this:
setup.override.edit_docModuleUpload = 0
NOTE: This only works for UserTS NOT for pageTS. (Thanks to Thomas Scholze for the hint!)
If you found a mistake or if you have a good tip or suggestion, please contact me at thomas(at)typo3-unleashed.net. I will check it and correct the entry or insert the new one.
Thanks in advance for your help.